Process for the production of castings by the centrifugal method



Patented Jan. 19, 1937 UNITED STATES PATENT OFFICE PROCESS FOR THE PRODUCTION OF CAST- INGS BY THE CENTRIFUGAL METHOD No Drawing. Application February 7, 1935,

Serial No. 5,403. In Germany March 26, 1934 Claims. (CL 22-192) This invention relates to a process for the proa binding medium in conjunction with the coatduction of castings by the centrifugal method. ing material, to facilitate the adhesion of the In the case of pipes and other castings produced powdered material to the wall of the mold. Genin stationary molds, it has already been proposed erally speaking, the amount of the coating comto provide the products with a special protective position will be calculated so as to sufllce for one 5 skin by lining the walls of the mold with corrocasting, and renew it after each casting has been sion-proof materials which penetrate into the made. I surface of the hot mass of the poured material Under the action of the phosphorus, the outer forming the casting, the anti-corrosion properties skin of the pipe acquires an increased content of said skin being intended to exceed those inof phosphorus, thereby imparting to'the said skin 10 herent in the ordinary castings. Acid-resisting -a high passivity and powers of resistance to the metallic alloys have also been proposed for such action of the acids and the like corrosive agents, linings. However, no definite statements have in the soil. At the same time, ferro-phosphorus been made respecting the nature of these subhas the advantage over other dusting materials stances and the manner of their application. that it is easily ground to powder and-in con- 15 Moreover, in connection with the production of trast to other ferro-alloys, such as ferro-silicon, centrifugal castings in chill molds, it has already form-chromium, and the like, which are substanbeen proposed to line the rotary molds with tially composed of heavy'metals-has alow meltferro-sllicon, or ferro-aluminium, prior to the n point, inasmuch as one of its comp n s pouring operation. Such lining is intended to consists of the readily fusible phosphorus. Con 20 modify the quenching action "of the walls of the sequ nt other su s s a li i conjuncmold and, n th th hand, by reason of its tion with ferro-phosphorus, in the form of powcolltent O s con or aluminium, to favor the der to the surface of the mold, fuse readily into formation of graphite on the outer layer of the the surface of the basic metal of the casting. pipe, in order to obtain cast pipes with a, soft since, in this case, the readily fusible phosphorus outer skin. alloys serve as a flux for other sintering mate- According to the present invention, centrifuria s of h r melting 1 galiy cast pipes with corrosion-proof outer skin pp r ph sphide, which can also be emp y can be produced ina centrifugal chill mold by with advantage in the production of centrifugal introducing into the mold, prior to casting, a lincastings of non-ferrous metallic alloys, has been ing composition composed of an alloy of phosfound to exert a like favorable effect. phorus which burns or fuses into the external Favorable results are for instance obtained with layer of' the pipe during th casting process, a lining of ferro-phosphorus containing about Alloys of phosphorus with the basic material of 20- %p p a d a out 8 0% iron: The the casting can be employed with particular addesired action of the applied ferro-phosphorus vantage, for example, compositions containing begins at a certain minimum amount which de-' ferro-phosphorus may be used as a lining on pends upon the casting material, and the crosscentrifugal molds for the casting of iron pipes, section and wall-thickness of the articles to be or. a material containing copper phosphide may cast. Said lowest amount necessary for produc- 40 be used in the production of copper pipes, The ing the desired effect may be easily determined 40 phosphorus alloys are preferably employed in a in each particular case. It must, however, be highly concentrated form, and therefore with a noted that the produced action will be diminhigh phosphorus content, it being important to ished if the ferro-phosphorus is used in amounts obtain the greatest possible e'ifect from a given which are too large as to be completely absorbed quantity of the coating composition. by the casting material. The most favorable ef- 45 The distribution of the coating material over feet is produced by using the ferro-phosphorus the interior wall of the mold is preferably effected in the highest amounts which still can be comby centrifugal force. In order to obtain uniform pletely dissolved at the temperature and walldistribution of the material over the entire length" thickness prevailing in each special case. Said of the rotary mold, it is advisable to employ the maximum moreover depends upon its special 50 coating material in theform of powderand feed composition and more a particularly upon the it into the mold by means of an axially dismelting-point thereof and its afllnity to the castilaeeable charging device. It is also. feasible to lug material; For instance, the favorable amount blow the powdered material into the mold. In for a ferro-phosphorus powder of the above mensome cases it has been found advisable to employ t'ioned composition (20-39% phosphorus and 5 70% iron) amounts to between about -60 grms. per square meter of the surface of the mold to be lined, in the case of the manufacture of cast iron tubes of an average cross-section and of average wall-thickness.

What I claim and desire to secure by Letters Patent of the United States is:

1. A process of producing a casting in a centrifugal mold which comprises applying a lining including an alloy of phosphorus to at least a portion of the mold, and then pouring molten metal into the lined mold, thereby forming a casting having the surface which contacted the lining enriched in phosphorus.

2. A method of producing a casting in a centrifugal mold which comprises applying a lining to at least a portion of the mold surface including a phosphorus alloy of the metal to be cast, and then pouring metal into the rotating mold and over the lining, thereby forming a casting having an exterior surface enriched in phosphorus.

3. A method of producing cast iron'pipe in a centrifugal mold which comprises applying a lining of pulverulent material including ferro-phosphorus containing 20 to 30% of phosphorus and 80 to of iron to at least a portion of the mold, and then pouring molten iron over the lining to form a pipe having the surface in con- 7 tact with the lining enriched in phosphorus.

4. In a method of casting iron in a chilled centrifugal mold, the step which comprises applying to the mold surface pulverulent ferro-phosphorus containing 20 to 30% of phosphorus and to 70% of iron, said pulverulent ferro-phos-' phorus being applied in an appreciable quantity but not exceding 60'grams distributed over one square meter of mold surface.

5. A centrifugal mold having at least a portion of the casting surface thereof lined with a pulverulent alloy containing an appreciable percentage of phosphorus.

"CARL PARDUN. 

